Edge computing is a technology emerging with the ongoing evolution of mobile networks into 5G (5th generation wireless mobile network standards). Edge computing relates to placing processing and storage capabilities (referred to as the “cloud”) closer to the user equipment (UE) in a mobile network. The edge cloud enables locally running different types of user and system services, thereby decreasing latency and volume of data transferred across the network. Applications deployed locally (i.e., executed in the edge cloud for users connected at the network edge) run faster and have higher throughput than when the service endpoint is in the core network or on the Internet.
Legal interception (LI) and charging functions run in the network core but use local data, and thus must have support within the edge cloud. The interfaces to LI/charging functions are defined in 3GPP (3rd Generation Partnership Project), a known group of standards documentation. Traffic to/from UE connected to the edge cloud may be copied and forwarded to the network device that performs LI. Information related to the UE's activity (known as logs) is provided to the charging function to enable it to generate billing information.
In current systems, LI and charging functions operate in the user-plane part of a PGW, per client, using a state record for the client using UE. Note that a client has a network subscription and accesses the network using his credentials via UE (i.e., the physical device). UE as a physical device may be used by different clients. However, since often a single client may use UE, the term “UE” and the terms “client” or “user” in this document mean a network subscriber using the physical device to log into the network, uniquely identified by the network core. The state records of clients are stored in state tables, which are updated to reflect the actual state.
Meaning of some standard notation used in this document are listed below:                APP Application        CP Control Plane        eNB evolved Node B        GW Gateway        HSS Home Subscriber Server        LTE Long Term Evolution (4th generation wireless mobile network standards)        OCS Online Charging System        OFCS Offline Charging System        MME Mobility Management Entity        PDN Packet Data Network        PGW PDN Gateway        SGW Serving Gateway        UP User Plane        
In order to improve scaling of the user-plane/control-plane, the PGW is may be implemented as a split user-plane/control-plane architecture as exemplary illustrated in FIG. 1. UE 110 accesses the network via base station 120, and uses various applications executed in the edge cloud, via user-plane gateway (UP-GW) 130. Traffic break-out (TBO) function 140 splits user-plane traffic (represented by a continuous line) into edge traffic and traffic to the network core. Dashed lines in FIG. 1 represent control-plane traffic, for example, from base station 120 to MME 150. The UP session status information, which corresponds to content of the state tables, enables UP-GW 130 to decide whether and what type of information to forward for LI/charging function execution.
SGW 155 and PGW 160 are divided into user-plane and control-plane architecture. The LI/charging functions are part of the PGW functionality. PGW 160 executes the LI and charging functions for UE 110. If a UE is target of legal interception, then PGW 160 supplies the summoned information to the legal interception system 170. The control-plane part of PGW 160 controls UP-GW 130, and is able to operate as a centralized controller for many UP-GWs that may be placed at different sites. Various other functional blocks and interfaces marked in FIG. 1 are described in 3GPP standards documentation and are, therefore, not detailed here.
Thus, the LI and charging functions are partly user-plane and partly control-plane functions. The LI function targeting a user triggers user-plane copying of packets of the targeted user, which are then sent from the edge site to the network core with appended header information for further analysis. The charging function may be a bucket-charging type, which requires counting bytes of the passing packets to produce a log that is sent over the charging interfaces to the billing system.
From a location perspective as illustrated in FIG. 2, TBO, UP-GW and edge computing resources may be placed on a hub 200, which is physically close to plural cells 210, at a network edge site. Note however that other cells 212 and 214 adjacent to cells 210 may be served connected to other hubs or even with other instances of the core network. Functions executed at the core-network site 220 communicate with the hub via S1-type interfaces in the control-plane (CP) and the user-plane (UP) respectively (i.e., S1-UP and S1-CP). The cell-sites (i.e., sites where antenna is placed) may be simple base-station-only sites or hub-sites. The hub-site usually includes base station and transmission aggregation functionality concentrating the backhaul transmission to several base stations providing edge computing for plural base stations. Thus, besides base station functionality, the hub may include router/switching for transport aggregation functionality, TBOs, cloud platform and core-network functions.
As already mentioned, execution of the LI/charging function is based on a per-client state recorded by the state records and reflected as UP session status information of an edge-connected user in the UP-GW. This information indicates the appropriate treatment of users' packets passing through a node. Currently, this state is statically configured by the management interfaces of the LI/charging function, with no mobility impacting the UE status information's storage location.
A problem with LI and charging functionality in the edge cloud is that a mobile UE often changes the serving base station, triggering a handover process between base stations. The PGW, which is fixed, provides a central anchor for the LI/charging functions, but the UP-GW may be changed (e.g., another UP-GW for one of cells 212 or 214). In order to properly process user's packets, the UE's status information has to be relocated on a new UP-GW when UP-GW is changed during the handover. Importing such UE status information from the network core does not reliably ensure continuity of the LI and charging functions.
Therefore, it is desirable to develop techniques for effectively maintaining the status information at the edge, with the status information being used to determine UE-related data to be forwarded to the network core for execution of LI and charging functions.